Air injecting apparatus for air conditioners or the like

ABSTRACT

The invention relates to an air conditioning system inlet assembly which has walls which form a chamber having an outlet opening. A pivotally mounted valve plate varies the size of the opening. The valve plate forms one lever arm of a fulcrumed lever and the second lever arm thereof is counterweighted. Weights on the second lever arm balance the biasing forces of pressurized air in the chamber which tend to move the valve plate in closing direction. An increase in the total volume of air supplied per unit time results in a larger valve opening to counter the effects of unpleasant drafts which would otherwise occur.

United States Patent De Lepeleire AIR INJECTING APPARATUS FOR AIRCONDITIONERS OR THE LIKE Guido Amandus De Lepeleire, Heverlee, BelgiumDanfoss A/S, Nordborg, Denmark Filed: Oct. 7, 1974 Appl. No.: 512,543

Related US. Application Data Division of Ser. No. 356,498, May 2, 1973,Pat. No. 3,865,021.

Inventor:

Assignee:

US. Cl 98/102; 98/37 Int. Cl. F24F 13/10 Field of Search 98/40 C, 40 D,106, 118,

References Cited UNITED STATES PATENTS 7/1963 Pratt 98/37 PrimaryExaminer--William E. Wayner Assistant Examiner-William E. Tapolcai, Jr.

[57] ABSTRACT The invention relates to an air conditioning system inletassembly which has walls which form a chamber having an outlet opening.A pivotally mounted valve plate varies the size of the opening. Thevalve plate forms one lever arm of a fulcrumed lever and the secondlever arm thereof is counterweighted. Weights on the second lever armbalance the biasing forces of pressurized air in the chamber which tendto move the valve plate in closing direction. An increase in the totalvolume of air supplied per unit time results in a larger valve openingto counter the effects of unpleasant drafts which would otherwise occur.

4 Claims, 7 Drawing Figures U.S. Patent Dec. 16, 1975 Sheet20f23,926,102

AIR INJECTING APPARATUS FOR AIR CONDITIONERS OR THE LIKE Thisapplication is a division of Ser. No. 356,478 filed May 2, 1973, nowU.S. Pat. No. 3,865,021.

The invention relates to an air injecting apparatus for air conditionersor the like, comprising an injection orifice through which a variablevolume of air passes.

In air conditioning and ventilating installations it is known to takeinto account a higher cooling load in the room that is being providedwith air by supplying the room with a larger volume of air per unittime. The air that is thus controlled is blown into the room throughinjection orifices having a constant cross-section. In some cases thisvolume control can be combined with the regulation of other parametersof the injected air, e.g. the temperature. With such air injectingapparatus there are, however, disadvantages. In particular,uncomfortable draughts occur during at least some operating conditions.Also, there are often disturbing noises.

The object of the invention is to provide an air injecting apparatus ofthe aforementioned kind in which the described disadvantages can beentirely or partially avoided with a mechanically simple construction.

This object is achieved in accordance with the invention in that thesize of the injection orifice is adjustable in relation to the angularposition of a lever having a pressure plate which is subjected to thepressure of the injected air in a chamber upstream of the injectionorifice in one direction of rotation and to a mechanical force in theopposite direction of rotation.

With this construction, the set orifice is controlled in dependence onthe pressure of the injected air in the upstream chamber. However, thespeed of injection varies in accordance with this pressure and the sizeof the injection orifice and it is this injection speed that is largelyresponsible for the disadvantages that have hitherto been observed. Inaddition, the control of the size of the injection orifice makes itpossible to take into account other parameters which influence the flowin the room. The lever subjected to the pressure and the mechanicalforce gives rise to a condition of equilibrium which determines the sizeof the injection orifice in a simple manner.

It is particularly advantageous if the pressure plate bounds one side ofthe upstream chamber and carries at its free end a limiting edge of theinjection orifice. The lever here serves to bound directly the upstreamchamber and the injection orifice.

For an injection orifice of gap shape, the limiting edge can here beformed by an end wall which adjoins the pressure plate and extendssubstantially perpendicular thereto. This end wall will then exert notorque on the lever. This will be so if the end wall is part of acylinder having its axis coincident with the rotary axis of the lever.

It is also recommended that the limiting edge be sharp-edged by means ofa chamfer on the side of the end wall remote from the rotary axis of thelever. This to a large extent suppresses disruptive torques emanatingfrom the limiting edge.

In practice, a lever has proved particularly suitable which has twoarms, one of which comprises the pressure plate and the other of whichis subjected to the mechanical load. A construction which isparticularly less prone to disturbance is one where the mechanical forceis formed by a weight. This weight can be adjustable along the secondarm, whereby an accurate adjustment of the apparatus is made possible onsite.

There are various possibilities of control that can be used depending onthe nature of the disturbing influence that is to be removed. There arealso possibilities of combination, e.g. such that in one limiting rangea first control function predominates and in another limiting range asecond control function predominates.

Thus, it is desirable to make the torque exerted on the lever by themechanical force substantially independent of the angular position ofthe lever. This will then ensure that the pressure in the upstreamchamber remains substantially constant. This results in a substantiallyconstant injecting speed despite a variable volume. In this way it ispossible to keep the injection speed so low under all operatingconditions that no disturbing noise will be set up.

When using a weight this control function is achieved if the second armcarrying the weight extends substantially horizontally because changesin the angular position of the lever have little influence on the torqueoccasioned by the weight.

In another manner of control, provision is made that the torque exertedon the lever by the mechanical force is dependent on the angularposition of the lever in such a way that the size of the injectionorifice is substantially proportional to the pressure in the upstreamchamber. In this way the archimedian number of the injected air can bekept substantially constant if its temperature remains unchanged. If theflow of air extends partially along the ceiling of the room by utilisingthe Coanda effect during normal operation, one can in this way preventthe flow from leaving the ceiling when the archimedian number exceeds acritical value.

This can be achieved with the use of a weight in that the second armcarrying the weight is inclined obliquely downwardly in the restposition of the lever.

Another possibility of control consists in that the torque exerted onthe lever by the mechanical force is dependent on the angular positionof the lever in such a way that the size of the injection orificechanges substantially inversely proportionally to the square of thepressure in the upstream chamber. As will be derived from the theoryconcerning geometrically similar chambers in the theory of flow, withthis control function the air flow maintains a particular course even ifthe volume of injection changes. This is particularly so for injectionorifices in the form of a horizontal gap lying substantially in avertical plane.

This can be achieved with the use of a weight in that the second armcarrying the weight is inclined obliquely upwardly in the rest positionof the lever. This construction also has the advantage that the secondarm and the weight can be conveniently accommodated in the interior ofthe air injecting apparatus.

Generally, the pressure plate will extend substantially horizontally.But there are also constructions, e.g. for injection orifices from whichthe air flows upwardly, in which an upwardly directed pressure platemust be provided. In this case a counterweight balancing out the weightof the pressure plate should be provided on the lever below the rotaryaxis.

In a preferred construction, the rotary axis is provided at the end of awall of the housing upstream of the pressure plate and an extension ofthis way surrounding the rotary axis forms between itself and the axis agap which is directed so that leakage air leaves it 3 substantiallyparallel to the pressure plate. This leakage air will in that casecreate no more than a negligible disruptive torque. If there is to beeven less leakage air, it is recommended that the gap between the rotaryaxis and the adjoining wall of the housing be covered by a thin sealingdiaphragm.

Further, the pressure plate may comprise two side walls extending up tothe end wall and overlapped in the region of the rotary axis by sidewalls of the housmg.

To reduce the air speed in the upstream chamber without enlarging thedownwardly projecting structural components, it is recommended that thefixed limiting edge of the injection orifice be bounded by a fixed endwall extending substantially parallel to the movable end .wall.

The invention will be described in more detail by way of preferredexamples shown in the drawings wherein:

FIG. 1 is a diagrammatic representation through a room equipped with anair injecting apparatus accord ing to the invention;

FIG. 2 is a diagrammatic representation of a modified example;

FIG. 3 is a diagrammatic representation of a third example;

FIG. 4 shows the outside of an air injecting apparatus to be mountednear the ceiling;

FIG. 5 is an enlarged view of a seal between the housing and the leveraxis;

FIG. 6 is a diagrammatic representation of a further embodiment havingan upwardly directed injection orifice, and

FIG. 7 is a further modification.

A room 1. is provided with air at a predetermined temperature through asupply conduit 2. The air is withdrawn again through a conduit 3. Athermostat 4 in the room 1 controls a throttle element 5 so that acontrol of the injected volume is achieved in dependence .on therequired cooling load. Between the supply conduit 2 and the room 1 thereis an air injecting apparatus 6 which is in this case in the form of awall mounting unit.

This apparatus 6 comprises an injection orifice 7 and a chamber 8upstream thereof which also acts as a sound suppresser by reason ofbeing cladded with an insulating layer 9. An important component of theair injecting apparatus is a lever 10 with the aid of which the size ofthe injection orifice 7 can be varied.

This will be explained in more detail .in conjunction with FIG. 2.

The lever 10 is pivotable about an axis 11. One lever arm is in the formof a pressure plate 12 at the free end of which there is provided an endwall 13. This has the shape of a cylinder of which the axis coincideswith the rotary axis 11. The upper edge of the end wall 13 is providedwith a chamfer 14 at the outside and forms a sharp limiting edge 15 ofthe injection orifice 7. The upper fixed limit is formed by a wallsurface 16.A second lever arm 17 is in the form of a rod which carries aweight 18 that is adjustable along the rod. The lower wall 19 of theapparatus 6 has an extension 20 which surrounds the rotary axis 11 and,together with it, forms a gap 21 through which leakage air can flow outsubstantially only parallel to the pressure plate 12.

If a certain volume of air is to be injected per unit time, a pressurep, depending on the size of the injection orifice 7 will obtain in theupstream chamber 8. This pressure acts on the pressure plate 12 andgives rise to a clockwise torque which is proportional to this pressure12 the area of the pressure plate 12 and the length 1,, up to the middleof the plate 12. Since the lastmentioned quantities are constant, thetorque is proportional to p The weight 18 gives rise to a torque in theopposite direction. This torque is proportional to the weight 18, thelength I and to cos (a 04). Since the two firstmentioned quantities areconstant, this torque is proportional to the angular function but it ispossible to provide a certain basic position by adjusting the weight 18along the rod 17. The angle a is determined by the rest position of thelever 10. FIG. 2 illustrates an operating condition at which theinjected air enters the room 1 with an injection speed v. By changingthe size of the injection orifice 7 and a corresponding change in thepressure p the injection speed v will also change. It can be shown thatthe following condition will to a large extent apply:

In FIG. 1 use is made of a lever 10 for which d 0. This ensures that ona change in the injected volume the injection orifice 7 will be enlargedto such an extent that the pressure p and thus also the speed v remainsubstantially constant. This speed can be set by adjusting the weight 18along the rod 17. There is no difficulty in keeping it below thecritical value that leads to disturbing noises.

In the FIG. 2 embodiment the angle (t is positive. A higher pressure pand thus a higher speed v is therefore associated with a smaller size ofthe injection orifice 7. By appropriately choosing the angle (1 it ispossible in the operating range of the lever 10 substantially to fulfillthe condition v l constant, where l is the height of the injectionorifice 7 in the form of a gap. From the theory of geometrically similarchambers in the theory of flow it can be shown that for this condition aselected course of flow will be maintained even when-the injected volumechanges. A very favourable course of flow is indicated by the line a inFIG. 1. The flow from the injection orifice 7 in the side wall is sodirected that it will impinge on the opposite side wall somewhat abovethe floor. If the injection speed drops on a decrease in the injectedvolume but if the injection orifice 7 were to remain constant, a courseof flow according to the line b would occur. By means of the describedcontrol of the injection orifice 7 the course of flow according to theline a can be substantially maintained.

FIG. 3 shows an embodiment in which the injection orifice 7 extends at avery small spacing below the ceiling of the room. This results in a flowaccording to the line d because the injected air will adhere to theceiling as a result of the Coanda effect. This, however, will only applyas long as a critical limiting value of the archimedian number A, forthe Coanda effect is not exceeded. This archimedian number is defined asfollows:

changed in proportion to v.

This can be substantially achieved by prescribing a negative angle (1 ofrest. With an increase in pressure p and thus an increased injectionspeed v, the lever will be set to a new condition of equilibrium atwhich the injection orifice 7 is larger. In this embodiment the pressureplate 12 is integrally bent to a bounding surface 22 for the orifice 7.

FIG. 4 illustrates an air injecting apparatus 6 to be accommodated inthe ceiling and of which only the lower portion 23 is disposed below thelevel D of the ceiling. The limiting surfaces of the apparatus 6 areagain bounded by sound-proofing walls 9. In the vicinity of the pressureplate 12, the lever 10 is not only provided with an end wall 13 but alsowith side walls 24 which are overlapped by the side walls of thehousing.

FIG. 5 shows a differentkind of seal between the rotary axis 11 and theadjacent wall 19 of the housing. Here, a thin diaphragm 26 covers thegap between the said parts.

FIG. 6 shows what measures must be taken if the pressure plate 12extends vertically upwardly because an upwardly directed flow is to passthrough the outlet 7. Apart from the arm with the pressure plate 12 andthe arm 17 with the weight 18 there is a further lever arm provided witha weight 27. This weight balances out the weight of the pressure plate12 so that stable operating conditions will obtain and the weight 18will, as in previous cases, give rise to a torque which acts against thetorque produced by the pressure p,. In the FIGS. 1 to 3 embodiments, thetorque produced by the pressure plate 12 can be taken into account by aportion of the weight 18.

In the embodiment of FIG. 7 the chamber 8 upstream of the injectionorifice 7 is enlarged in that the wall 9 in the region of the orifice 7comprises a downwardly projecting end surface 28. This ensures that thespeed in the upstream chamber 8 is in any case considerably lower thanthe injection speed v without the apparatus requiring an excessivelylarge constructional height beneath the orifice 7.

There are possibilities alternative to the weight 18 to bring about acertain functional relationship between the counter-torque and theangular position of the lever 10 with the aid of a mechanical force. Forexample, the mechanical force can be produced by a spring. For thispurpose springs having a non-linear characteristic will be particularlyapplicable.

I claim:

1. An air conditioning system air inlet assembly comprising an air flowduct, a damper forming a variable outlet orifice for said duct, saiddamper being mounted for pivotal movement relative to a horizontallyextending axis, said damper being movable in an opening direction bypressurized upstream air in said duct, mechanical means biasing saiddamper in a closing direction, said mechanical means having an angularrelationship with said damper to vary the size of said orifice inaccordance with the pressure of said pressurized air to maintain aconstant air velocity at said orifice, said duct extending vertically,said damper constituting a first lever arm relative to said axis, saidmechanical means including a second lever arm extending in a generallyhorizontal direction.

2. An air inlet assembly according to claim 1 wherein said second leverarm has weight means associated therewith, said second lever arm havingan attitude angle relative to said first lever arm so that said damperforms an opening proportional to the air pressure of said chamber.

3. An air inlet assembly according to claim 1 wherein said second leverarm is inclined obliquely downwardly in its at-rest position.

4. An air inlet aseembly according to claim 1 wherein said damper has aflat part which extends generally verfically, and weight means beingmounted on said first lever arm belowsaid axis.

1. An air conditioning system air inlet assembly comprising an air flowduct, a damper forming a variable outlet orifice for said duct, saiddamper being mounted for pivotal movement relative to a horizontallyextending axis, said damper being movable in an opening direction bypressurized upstream air in said duct, mechanical means biasing saiddamper in a closing direction, said mechanical means having an angularrelationship with said damper to vary the size of said orifice inaccordance with the pressure of said pressurized air to maintain aconstant air velocity at said orifice, said duct extending vertically,said damper constituting a first lever arm relative to said axis, saidmechanical means including a second lever arm extending in a generallyhorizontal direction.
 2. An air inlet assembly according to claim 1wherein said second lever arm has weight means associated therewith,said second lever arm having an attitude angle relative to said firstlever arm so that said damper forms an opening proportional to the airpressure of said chamber.
 3. An air inlet assembly according to claim 1wherein said second lever arm is inclined obliquely downwardly in itsat-rest position.
 4. An air inlet aseembly according to claim 1 whereinsaid damper has a flat part which extends generally vertically, andweight means being mounted on said first lever arm below said axis.